[LLVMdev] recreate optimized clang output

[Hendrix_ at gmx.net]

Hi,

I was using "clang  -O3 -S -emit-llvm" got some very optimized output.

Then I did "clang -S -emit-llvm" (without optimization) and wanted to optimized the code in a
separate pass. The llvm program "opt" did not do anything.

How can I invoke the optimizer on some un-optimized program, possibly showing the output of each optimizer stage?
I would like to get a deeper understanding of the optimization pass.

Best,
Patrick